Aromatic hydrocarbons from terpenes

Britt, PR, A.C. Buchanan iii, and C.V. Owens Jr Eormation of polycyclic aromatic hydrocarbons from the gas-phase pyrolysis of terpenes and steryl esters at short residence times 55th Tobacco Science Research Conference, Program Booklet and Abstracts, Vol. 55, Paper No. 20, 2001, p. 32. 

Organic aerosols formed by gas-phase photochemical reactions of hydrocarbons, ozone, and nitrogen oxides have been identified recently in both urban and rural atmospheres. Aliphatic organic nitrates, such dicarboxylic acids as adipic and glutaric acids, carboxylic acids derived from aromatic hydrocarbons (benzoic and phenylacetic acids) and from terpenes emitted by vegetation, such as pinonic acid from a pinene, have been identified. The most important contribution in this held has been that of Schuetzle et al., who used computer-controlled... 

Isoprenoid structures for carotenoids, phytol, and other terpenes start biosynthetically from acetyl coenzyme A (89) with successive additions giving mevalonate, isopentyl pyrophosphate, geranyl pyrophosphate, farnesyl pyrophosphate (from which squalene and steroids arise), with further build-up to geranyl geranyl pyrophosphate, ultimately to a- and /3-carotenes, lutein, and violaxanthin and related compounds. Aromatic hydrocarbon nuclei are biosynthesized in many instances by the shikimic acid pathway (90). More complex polycyclic aromatic compounds are synthesized by other pathways in which naphthalene dimerization is an important step (91). 

The kinetics of the reactions of many xenobiotics with hydroxyl and nitrate radicals have been examined under simulated atmospheric conditions and include (1) aliphatic and aromatic hydrocarbons (Tuazon et al. 1986) and substituted monocyclic aromatic compounds (Atkinson et al. 1987c) (2) terpenes (Atkinson et al. 1985a) (3) amines (Atkinson et al. 1987a) (4) heterocyclic compounds (Atkinson et al. 1985b) and (5) chlorinated aromatic hydrocarbons (Kwok et al. 1995). For PCBs (Anderson and Hites 1996), rate constants were highly dependent on the number of chlorine atoms, and calculated atmospheric lifetimes varied from 2 days for 3-chlorobiphenyl to 34 days for 2,2, 3,5, 6-pentachlorbiphenyl. It was estimated that loss by hydroxylation in the atmosphere was a primary process for removal of PCBs from the environment. It was later shown that the products were chlorinated benzoic acids produced by initial reaction with a... 

Leopold Ruzicka s structural studies of hydrocarbons, also in collaboration with the perfume industry (see chapter 3), took Wallach s terpene studies to a new level. He smdied the dehydrogenation of monoterpenes (to formp-cymene) as well as the dehydrogenation, using selenium (Diels reaction), of sesquiterpenes (C15), diterpenes (C20), and triterpenes (C30), and dehydrogenated them (via the Diels reaction, to form aromatics derivatives of naphthalene, anthracene, chrysene, and others). During the 1920s Ruzicka postulated that steroids are derived from terpenes and, in... 

Most solvent products, especially organic solvents and some additives, emitted from paints and varnishes are VOCs. The largest components of VOCs are solvents, e.g., aliphatic and aromatic hydrocarbons, alcohols, amines, acids, aldehydes, esters, ketones, terpenes. The definition of flic term VOC varies, a standard definition is published by CEN (European Committee for Standardization) VOCs are any organic liquids and/or solids that evaporate spontaneously at the prevailing temperature and pressure of the atmosphere. 

Some aromatic hydrocarbons are probably generated in spices by terpene oxidation. Examples are l-methyl-4-isopropenylbenzene (XI, Formula 22.3) derived from p-men-tha-l,3,8-tri-ene (X) and (+)-ar-curcumene (XIV) from zin-giberene (XII) or 3-sesquiphel-landrene (XIII) [cf. Formula 22.4]. 

A mixture of hydrocarbons can be separated by three selective adsorbents molecular sieves which retain the n-paraffins, mercuric perchlorate which adsorbs the unsaturated compounds, and a stationary liquid phase which retains the aromatic hydrocarbons. Boric acid on a stationary phase such as Chromosorb P is used for the removal of alcohols from a mixture of organic compounds, the products are nonvolatile esters. A similar technique was used for removal of terpene alcohols from a mixture of terpenoids. Acids can be adsorbed on potassium hydroxide deposited on quartz powder. This technique was found to be suitable for the analysis of compounds having active hydrogens such as fluorene, indene, carbazole, indole, and pyrrole as well as steroids such as estrogens and ketosteroids. o-Dianisidine quantitatively subtracts aldehydes, ketones, and epoxides, and phosphoric acid subtracts epoxides. 

Dicarbonyls. A third area of uncertainty is the treatment of dicarbonyls formed from aromatic or terpene hydrocarbon oxidation. (The simplest is glyoxal, CHOCHO, but a large number have been identified, 47. The yields and subsequent reactions of these compounds represent a major area of uncertainty in urban air photochemistry (186) and since they may be a significant source of HOjj through photolysis, inaccuracies in their portrayal may result in errors in calculated values of HO. and HO2.. 

Considerable attention has been directed in determining the products from reactions of aliphatic hydrocarbons, aromatic compounds, and unsaturated compounds including biogenic terpenes that exhibit appreciable volatility. These studies have been conducted both in simulation chambers and using natural sunlight in the presence of NO. 

Most users feel mental effects from ground nutmeg with a 20 gm. dose, which has been assayed at 210 mg. myristicin (potential MMDA), 70 mg. elemicin (potential TMA), 39 mg. safrole (potential MDA), plus smaller amounts of other aromatic ethers and a number of terpene hydrocarbons (biological irritants). 

The USDA characterized a large number of biomass species for their traditional composition fractions of ash, crude protein, polyphenols, oils and hydrocarbons among others. These fiactions were defined operationally by the USDA botanochemical screening project their sample analysis and fraction partitioning scheme is summarized in Fig. 1. Of interest were extractives, components that can he separated/paititioned from the plant by solvents. The major extractives included various oils, terpenes, fatty acids, unsaponiflables, aromatic compounds, tannins, and quinones. In exceptional cases extractives composed over 15% of the biomass (especially ash) but generally they did not exceed S-10%. 

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